Hey all,

So I have a 2003 F150 and as summer is approaching and I am using my AC more. I have noticed that it blows cold air, but not quite as cold as it used to be. It gets colder when I go on the freeway and am accelerating or using the gas as opposed to just coasting down a hill. My AC used to be cold when I would coast, but now it just feels like there is no AC even on when I coast, but gets cold when accelerating etc. What can I do to try and make make the AC get back to being cold like it used to be?

 

Check for leaks, recharge the system, efans

 

For sure put gages on it for a accurate diagnosis!
Check for dirt in the condenser fins. If you wash it don't blast it because you will bend the fins with high pressure.

 

Honestly I have never done anything dealing with HVAC before, so is this something I can do myself or do I need to take it into a shop? If it is something I can do myself, are there any tutorials out there on it?

 

There are some things you can do yourself. At WalMart and most auto stores they sell refrigerant (R134A) and dyes with ultra violet lights. I have not used the dyes, but these can be used to check for leaks. I have had issues trying to add R134A to top off my refrigerant. It's suppopsed to be easy and the directions on the cans are pretty straight forward. But I had issues with the gauge that can on the first can. I bought a second can different brand and it seamed to work better. I have been out of town and haven't driven my truck much since the second can. So we'll see how it goes when I get back.

From what I have found, there are no tutorials or write-ups on adding R134 but read the back of the can. It's not difficult.

 

Heres a youtube video of the process http://www.youtube.com/watch?v=KyXA7UxjaDw

 

^^ He didn't purge the air from the line, and didn't check the pressure at engine operating speed. A system running at about 35 # of pressure at 600 rpm, is going to low pressure cycle at 1800 rpm. It will cool, but on a long trip the evaporator coil will freeze over causing a less than desirable condition for the A/C system. But it will work.

 

How do you purge the air from the line? And how do you check the engine at operating speed, just have someone push on the gas while you are checking the pressure?

 

^^One way is, a manifold gage set, you connect the lines to the system, and just crack the valves one at a time, to let any pressure from the system push the air out through the fill line. then put the fill valve (the part that pierces the can) on that line. Once that is done, you should never need to do it again. My set holds the pressure even while hanging in storage.
In the case of what he was doing in the video, he would pierce the can, and let the pressure from the can push the air out. Then close the valve on the can, then connect it to the accumulator. Or if it has a screw on connector at the can, connect the line to the accumulator and back the line line off at the can, much like the way of doing it on the manifold set.
It is more important to not get any humidity in your system, as than it is not to get air in it. Water combines with freon when going through the compressor and makes little rock looking ***** that will stop up the orifice tube, or the expansion valve(on some brands of units). Once freon and water are compressed together they form hydrochloric acid chunks

 

I forgot the second question. The answer is yes, get a second person to hold the throttle. It is hard to get it in the rpm range at first, but they can usually do after a couple of tries. As for doing it by yourself, it is very hard to turn the butterfly by hand and try to get an accurate pressure reading. But i have done it before.
The first reason for the rpms is because the suction from the compressor will get the freon out of the can.
The second reason is, that it is the operating speed of the compressor. If you watch your tach when driving. The automatic transmission keeps the engine in the 1500 to 2200 rpm range during normal driving

 

Tumba thanks for all of your help, I really appreciate it. I think I may just take it into the shop to see what they say as I am kinda afraid that I may mess something up and end up costing myself more money in the long run.

Thanks!

 

We have probably all done that at some time or another